How to Make Beurre Composé

The classic French enhanced butter is a cinch to prepare. This illustrated step-by-step guide shows you how

Sept. 20, 2013 4:31 p.m. ET

I TASTED BEURRE composé for the first time in Paris. The entrecôte I'd ordered came to the table with a nugget of beurre de Montpellier perched on top, melting languidly down the steak's sides. I'd thought of butter as an ingredient impossible to improve upon until I encountered this version, laced with a confetti of minced tarragon, anchovies, gherkins and capers. It was love at first bite.

Known in English as compound butter, it's not exactly a health food. But for me, the occasional hit goes a long way toward promoting utter satisfaction and cozy well-being; combined with fresh herbs, garlic, anchovies, reduced wine or stock, a ground spice or two, or some other highly flavored ingredient, it gives you more bang for your buck. In most cases, just a smidgen will transform a dish.

It's my favorite party trick, especially as it takes less than five minutes to blend the components and roll the result into a neat log that can be stored in the refrigerator for weeks, and in the freezer for months. Simply slice as needed and melt over meats, fish or poultry—an instant sauce. This bolder butter also boosts flavor when swirled into a soup or a more complex sauce.

Montpellier is but one of countless variations. Lemon zest and rosemary butters brighten poached salmon and roast chicken; a version enhanced with fresh mint confirms yet again that nothing is better with lamb than that cooling garden perennial. But I do not mean to suggest that you should reserve this under-utilized sauce for proteins. Compound butters dramatically amplify the flavor of vegetables, too. Try caper butter with roasted asparagus, fennel butter with steamed cauliflower, mint butter with sugar snap and English peas. Slather late-season corn with tarragon, cilantro, curry or any most any other variety of compound butter. Pasta, rice and grains likewise benefit from a pat or two, and any fresh herb butter turns a lowly baked potato into food fit for the gods.

The illustrated step-by-step instructions below are for fresh marjoram butter—a scrumptious accompaniment to swordfish steaks—but you can use the same steps to make any beurre composé. Try the variations provided, and then go to town with whatever is in season or in your pantry. After all, what doesn't taste better with a little butter?

—Gail Monaghan

The Ingredients

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Illustrations by Joe McKendry for The Wall Street Journal

The Steps

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Step 1
Illustration by Joe McKendry for The Wall Street Journal

1. Place all ingredients in a food processor and pulse until combined. Using a rubber spatula, spread butter in a strip across a large sheet of waxed paper or plastic wrap, leaving 1-2 inches at each end.

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Step 2
Illustration by Joe McKendry for The Wall Street Journal

2. Roll paper around butter and then roll back and forth to form a cylinder that is smooth and equal in size from end to end, 1-1½ inches in diameter.

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Step 3
Illustration by Joe McKendry for The Wall Street Journal

3. Twist paper at both ends of butter cylinder to close and refrigerate for at least an hour or until needed. Butter will keep in the refrigerator at least two weeks. For longer storage, wrap well in aluminum foil and freeze for up to six months.

Swordfish Steak with Fresh Marjoram Butter

Active Time: 15 minutes Total Time: 45 minutes Serves: 6

In a large shallow dish, mix 3 tablespoons olive oil with 2 tablespoons freshly squeezed lemon juice and 2 cloves garlic, crushed, and set aside at least 15 minutes. // Season six 8-ounce swordfish steaks with salt and pepper, add to dish with oil mixture and turn to coat. Set aside 15-30 minutes. // Place fish under the broiler and cook to desired doneness, 3-4 minutes per side for medium. Place a slice of cold marjoram butter (see above) on top of each steak and serve immediately.

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